Historically paper rolls, such as toilet rolls, are provided with a core of a relatively stiff material, usually cardboard. It is, however, not unusual that the circular cross-section of such a roll is deformed during storage, transport and use of such a paper roll, so that the cross-section becomes oval. An oval cross-section of the core prevents a smooth unwinding of paper from the roll.
Nowadays also coreless paper rolls are known. Coreless paper rolls are wound without a carton core directly upon a shaft to a “log”. When the log is finished, the shaft is drawn out to leave a hole in the centre of the log. The log is then cut sideways into correct width for customer rolls. The windings nearest the hole in the roll has a tendency to partly collapse, making the hole starshaped or in other ways uneven. An advantage by such rolls is that for the same outer diameters, a coreless paper roll contains more paper than a roll provided with a core. Another advantage compared to rolls with cores is that no waste material which has to be discarded exists after use of a coreless paper roll. A problem with coreless paper rolls is that the cross-section thereof can be deformed which results in difficulties in applying the roll in a dispenser and also an uneven unwinding of paper from a roll applied to a dispenser. This problem has been solved by providing end plugs to be inserted into one or opposite ends of a coreless paper roll depending on the type of dispenser being used.
Coreless paper rolls provided with correctly inserted end plugs are easy to apply to a dispenser and ensure a smooth unwinding of the paper on the roll.
It is desirable that such end plugs are tightly applied to the interior of the paper roll so that the roll can not slip in relation to the plug but will rotate together with the plug. Moreover, if the end plugs are inserted into the paper rolls in connection to manufacture thereof, i.e. before storing thereof and transport to the end consumer, it is important that the end plugs stay in place after insertion. In order to facilitate insertion of the end plugs these are often slightly conical or have a tapering insertion end. However, due to the deformation of a coreless paper roll it is sometimes difficult to fully insert end plugs which can result in difficulties in applying the paper roll to a dispenser. Furthermore, to ensure the desired function of a conventional cylindrical end plug, a tight fit between the interior surface of the roll and the outer surface of the plug is necessary. However, due to manufacturing tolerances for the rolls it can occur that an end plug having a perfect fit to one roll has a loose fit to another roll. There is thus a need for improvements of end plugs for coreless paper rolls.
The objective of the present invention is to fill this need and provide an end plug for coreless paper rolls which is easy to apply and which will fit tightly.